Hardset miniums on heating are not unusual in rental properties everywhere that needs heating, because turning the heat off entirely during a coldspell can cause very expensive damage to the property. Usually it is a bit more flexible and sane than just "Termostat, what termostat?" tough, but the broader point is that while adopting best-practice in insulation could probably cut Russias heating needs in half, half of "Oh, my fracking god" it is still going to be quite a high number.

Russia is quite heavily set on a nuclear path to decarbonization, and I dont really see that they have that much of a choice. - Russia has good hydro reserves, and quite substantial biomass waste from their forestry operations, but other renewable options do not really get along with russian weather. At all.
Not that carbon is why they are doing it - Russia is building reactors because burning gas that could be sold abroad is an affront to gasproms accountants, and the cold war left them with an enormous legacy of institutional expertise in all things related to fission.